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Display quiet NaNs as 'NaN'.

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This is recommended by IEEE 754-2008.

We still distinguish signaling NaNs with 'sNaN'.
This commit is contained in:
Jakob Stoklund Olesen
2016-04-05 10:20:32 -07:00
parent 5f706b0a1f
commit 79e765a183
2 changed files with 15 additions and 12 deletions
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7
docs/langref.rst
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@@ -247,6 +247,9 @@ Normal numbers
necessary for :type:`ieee64` which has 52 trailing significand bits
forming 13 hexadecimal digits with no padding.
Zeros
Positive and negative zero are displayed as ``0.0`` and ``-0.0`` respectively.
Subnormal numbers
Compatible with C99: ``-0x0.Tpemin`` where ``T`` are the trailing
significand bits encoded as hexadecimal, and ``emin`` is the minimum exponent
@@ -258,8 +261,8 @@ Infinities
Quiet NaNs
Quiet NaNs have the MSB of the trailing significand set. If the remaining
bits of the trailing significand are all zero, the value is displayed as
``-qNaN`` or ``qNaN``. Otherwise, ``-qNaN:0xT`` where ``T`` are the
trailing significand bits encoded as hexadecimal.
``-NaN`` or ``NaN``. Otherwise, ``-NaN:0xT`` where ``T`` are the trailing
significand bits encoded as hexadecimal.
Signaling NaNs
Displayed as ``-sNaN:0xT``.

20
src/libcretonne/immediates.rs
View File

@@ -99,9 +99,9 @@ fn format_float(bits: u64, w: u8, t: u8, f: &mut Formatter) -> fmt::Result {
if t_bits & (1 << (t - 1)) != 0 {
// Quiet NaN.
if payload != 0 {
write!(f, "qNaN:0x{:x}", payload)
write!(f, "NaN:0x{:x}", payload)
} else {
write!(f, "qNaN")
write!(f, "NaN")
}
} else {
// Signaling NaN.
@@ -186,12 +186,12 @@ mod tests {
"0x0.000002p-126");
assert_eq!(format!("{}", Ieee32::new(f32::INFINITY)), "Inf");
assert_eq!(format!("{}", Ieee32::new(f32::NEG_INFINITY)), "-Inf");
assert_eq!(format!("{}", Ieee32::new(f32::NAN)), "qNaN");
assert_eq!(format!("{}", Ieee32::new(-f32::NAN)), "-qNaN");
assert_eq!(format!("{}", Ieee32::new(f32::NAN)), "NaN");
assert_eq!(format!("{}", Ieee32::new(-f32::NAN)), "-NaN");
// Construct some qNaNs with payloads.
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fc00001)), "qNaN:0x1");
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fc00001)), "NaN:0x1");
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7ff00001)),
"qNaN:0x300001");
"NaN:0x300001");
// Signaling NaNs.
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7f800001)), "sNaN:0x1");
assert_eq!(format!("{}", Ieee32::new_from_bits(0x7fa00001)),
@@ -221,13 +221,13 @@ mod tests {
"0x0.0000000000001p-1022");
assert_eq!(format!("{}", Ieee64::new(f64::INFINITY)), "Inf");
assert_eq!(format!("{}", Ieee64::new(f64::NEG_INFINITY)), "-Inf");
assert_eq!(format!("{}", Ieee64::new(f64::NAN)), "qNaN");
assert_eq!(format!("{}", Ieee64::new(-f64::NAN)), "-qNaN");
assert_eq!(format!("{}", Ieee64::new(f64::NAN)), "NaN");
assert_eq!(format!("{}", Ieee64::new(-f64::NAN)), "-NaN");
// Construct some qNaNs with payloads.
assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ff8000000000001)),
"qNaN:0x1");
"NaN:0x1");
assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ffc000000000001)),
"qNaN:0x4000000000001");
"NaN:0x4000000000001");
// Signaling NaNs.
assert_eq!(format!("{}", Ieee64::new_from_bits(0x7ff0000000000001)),
"sNaN:0x1");